GM.xmlHttpRequest

Description

This method performs a similar function to the standard XMLHttpRequest object, but allows these requests to cross the same origin policy boundaries.

Syntax

function GM.xmlHttpRequest( details )

Compatibility: Greasemonkey 4.0+

Arguments

This method only takes one argument, the details object. Described below are the properties that may be defined on that object. See #Examples for more detail on how to use each.

Fields:

binary

Boolean Optional, default false. When true, the data is sent as a Blob.

context

Object (Compatibility: 1.10+) Optional, any object. This object will also be the context property of the #Response Object.

data

String Optional. Data to send in the request body. Usually for POST method requests. ^[1]

headers

Object Optional. A set of headers to include in the request. ^[2]

method

String Required. Type of HTTP request to make (E.G. "GET", "POST")

overrideMimeType

String Optional. A MIME type to specify with the request (E.G. "text/html; charset=ISO-8859-1").

password

String Optional. Password to use for authentication purposes.

responseType

String Optional. Decode the response as specified type. Accepted values are "", "arraybuffer", "blob", "document", "json", "text", "ms-stream". Default value is "text". See XMLHttpRequest responseType.

synchronous

Boolean Defaults to false. When true, this is a synchronous request. Be careful: The entire Firefox UI will be locked and frozen until the request completes. In this mode, more data will be available in the return value.

timeout

Number The number of milliseconds to wait before terminating the call; zero (the default) means wait forever.

upload

Object Optional. Object containing optional function callbacks (onabort, onerror, onload, onprogress) to monitor the upload of data. Each is passed one argument, the #Response Object.

url

String Required. The URL to make the request to. Must be an absolute URL, beginning with the scheme. May be relative to the current page.

user

String Optional. User name to use for authentication purposes.

Event handlers:

onabort

Function Optional. Will be called when the request is aborted. Passed one argument, the #Response Object.

onerror

Function Optional. Will be called if an error occurs while processing the request. Passed one argument, the #Response Object.

onload

Function Optional. Will be called when the request has completed successfully. Passed one argument, the #Response Object.

onprogress

Function Optional. Will be called when the request progress changes. Passed one argument, the #Response Object.

onreadystatechange

Function Optional. Will be called repeatedly while the request is in progress. Passed one argument, the #Response Object.

ontimeout

Function Optional. Will be called if/when the request times out. Passed one argument, the #Response Object.

Response Object

All of the callback functions defined in the details object, if called, will receive this type of object as their first (and only) argument. The data available will vary slightly, depending on the type of callback.

Properties based on a standard XMLHttpRequest object:

• readyState
• responseHeaders: String, with CRLF line terminators.
• responseText
• status
• statusText

Greasemonkey custom properties:

• context
Object The same object passed into the original request.

Properties for progress callbacks, based on nsIDOMProgressEvent:

• lengthComputable
• loaded
• total

Returns

undefined

Examples

Bare Minimum

GM.xmlHttpRequest({
  method: "GET",
  url: "http://www.example.com/",
  onload: function(response) {
    alert(response.responseText);
  }
});

GET request

GM.xmlHttpRequest({
  method: "GET",
  url: "http://www.example.net/",
  headers: {
    "User-Agent": "Mozilla/5.0",    // If not specified, navigator.userAgent will be used.
    "Accept": "text/xml"            // If not specified, browser defaults will be used.
  },
  onload: function(response) {
    var responseXML = null;
    // Inject responseXML into existing Object (only appropriate for XML content).
    if (!response.responseXML) {
      responseXML = new DOMParser()
        .parseFromString(response.responseText, "text/xml");
    }

    console.log([
      response.status,
      response.statusText,
      response.readyState,
      response.responseHeaders,
      response.responseText,
      response.finalUrl,
      responseXML
    ].join("\n"));
  }
});

POST request

When making a POST request, most sites require the Content-Type header to be defined as such:

GM.xmlHttpRequest({
  method: "POST",
  url: "http://www.example.net/login",
  data: "username=johndoe&password=xyz123",
  headers: {
    "Content-Type": "application/x-www-form-urlencoded"
  },
  onload: function(response) {
    if (response.responseText.indexOf("Logged in as") > -1) {
      location.href = "http://www.example.net/dashboard";
    }
  }
});

HEAD request

As defined in HTTP, you may issue a HEAD request to get the response headers, without receiving the entire response body.

GM.xmlHttpRequest({
  url: "http://www.example.com",
  method: "HEAD",
  onload: function(response) {
    console.log(response.responseHeaders);
  }
});

Notes

If the data field contains form-encoded data, you usually must also set the header 'Content-Type': 'application/x-www-form-urlencoded' in the headers field.